In a conventional or typical automotive-type internal combustion engine, intake air is drawn through an intake manifold to the combustion chamber in the cylinder head of the engine. Typically, the intake manifold includes a header or common chamber into which air is drawn from atmosphere (or through a carburetor) and a number of individual intake runners or legs lead from the header to intake ports formed in the cylinder heads. Typically, a carburetor or fuel-injection system delivers a metered amount of fuel into the airstream which is, in part, vaporized and atomized in the airstream in the intake manifold.
During operation of the internal combustion engine, air is drawn into the combustion chamber through the intake manifold where it is usually charged with fuel prior to entering or after entering the combustion chamber. Once the combustion chamber has drawn in sufficient air and/or fuel, an intake valve closes to close off the intake manifold from the combustion chamber. This closing of the intake valve causes the air progressing through the intake manifold to stop abruptly, to bounce off the closed valve, and sends a reversed flow echo up through the intake manifold. When the intake valve reopens and the next charge of air is to be drawn in, the air flow echo heading back up the intake then stops and reverses flow again toward the combustion chamber. A similar action takes place in the exhaust except with a push-pull motion. These actions result in a rather jerky motion of air and/or fuel and combustion gases within the intake and exhaust manifolds and results in reduced efficiency of the engine.
Conventionally, the goals of typical intake manifold designs are to provide good mass division, good quality division, and high volumetric efficiency at full throttle. See, Internal Combustion Engines and Air Pollution, Edward F. Obert, 3rd. Ed., Copyright 1973, Harper & Row, at pp. 420-421. Good mass division is achieved when the entering fuel, additives, and air are divided equally among the cylinders at all speeds and loads. Good quality division is achieved when the combustion charge received by each cylinder is well mixed and has the same physical and chemical characteristics.
It has been known in the prior art to try to achieve these goals by providing intake manifolds with similar passageways to all cylinders, turbulence inducers, localized hot spots to reduce large liquid droplets, and smooth interior walls to reduce the thickness of the liquid film flowing along the interior walls. For example, U.S. Pat. No. 2,390,913 of Barrett discloses the use of a large header having internal helical vanes to direct the air flow to individual cylinders. The runners of Barrett that lead from the header to the individual cylinders have smooth interior walls. U.S. Pat. No. 2,423,602 of Magdeburger shows a similar type of arrangement.
While current automotive manifold technology is adequate generally, them remains yet a need for a manifold which provides increased power and fuel efficiency. It is to the provision of such a manifold that the present invention is primarily directed.